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2008 Pontiac G5 Question: Why will my fan not kick on when my engines gets hot?

 

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tabatharyann, Cambridge, OH, August 14, 2013, 12:31
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My fan will not kick on....even when my car gets to 205 degrees. I have replaced fuses...and nothing! Please help. I was told that it could be a relay switch or a sensor to the fan. I do not know where this is located...can anyone tell me where to find this?

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    Justin Case Auto from Justin Case Automotive Repair, Inc., August 14, 2013, 13:33
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     Technician

    Not sure what engine you have so this is for a 2.2
    - Engine coolant fan should come on at low speed when engine temperature is 223 degrees or A/C high side pressure is 190 PSI.
    - High speed fan should operate at 230 degrees or 240 PSI on the A/C high pressure.
    Radiator cap has to hold good pressure and be on the system when testing or coolant will spit out of the filler neck.
    The best way to test is to have a scanner hooked into the computer system and read the actual temperature that the coolant sensor is giving the PCM

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    pushrod, August 14, 2013, 13:54
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     Master

    Agreed! -------That's pretty much the same for all vehicles with this type cooling system set up. They all seem like the fan is never going to come on, be patient, i bet it will come on before the engine gets HOT!

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    tabatharyann, August 14, 2013, 18:44
     Rookie

    My car is a 2.2. My thermostat light came on whil idle and temp read 258. So what is the normal temp on a car?

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    Justin Case Auto, August 15, 2013, 04:36
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     Technician

    Normal temp should be around 195-220 depending on fan operation. If the vehicle hit that type of temp and the fan still did not come on the next step is to...
    Run vehicle with a/c on and see if fan comes on. Should come on pretty quick because it will be off a/c pressure not coolant temp. If fan comes on you may have an electrical issue in the system and we will need more information to help with that but I'm going to assume that it will not come on due to the fact that I'm sure you would have noticed that already.
    There are 2 fuses and 2 relays in the underhood fuse block labeled COOL FAN 1 and COOL FAN 2. Test the fuses first, I know you replaced them but make sure you have voltage to and thru them (both sides of fuse). If they are good then with the vehicle running with a/c on (this way you don't have to overheat the engine to test) test for voltage at the radiator fan. There should be 3 wires, one Yellow is voltage to low speed, Grey is voltage to high speed and black is found. You should have voltage at one of the power wires. and the black should have none indicating it's grounded. If this is correct you have a bad fan motor.
    I'm also assuming you have a scanner due to the exact temp you know the vehicle was at... In your data there should be a PID to tell you if the computer has commanded on the coolant fan, check that it is on when testing the wires. There is also a possibility that your scanner will have bi-directional controls and you will be able to command the fan on so you can do your test with out the vehicle running.

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